1. Field of the Invention
The present invention relates to a spin-valve thin-film magnetic element in which electrical resistance changes due to the relationship between the pinned magnetization direction of a pinned magnetic layer and the magnetization direction of a free magnetic layer which is influenced by an external magnetic field, and to a thin-film magnetic head provided with the spin-valve thin-film magnetic element. More particularly, the invention relates to a technique which improves the output and stability of the element, which reduces Barkhausen noise, etc., and which allows satisfactory alignment of the domain of the free magnetic layer when the track width is narrowed.
2. Description of the Related Art
A spin-valve thin-film magnetic element is one type of giant magnetoresistive (GMR) element exhibiting a giant magnetoresistance effect, and it detects a recorded magnetic field from a magnetic recording medium, such as a hard disk.
The spin-valve thin-film magnetic element has a relatively simple structure among GMR elements, and has a high rate of resistance change relative to an external magnetic field, and the resistance changes in response to a weak magnetic field.
FIG. 35 is a sectional view of a conventional spin-valve thin-film magnetic element, viewed from a surface facing a recording medium (air bearing surface; ABS).
The spin-valve thin-film magnetic element shown in FIG. 35 is a so-called bottom-type single spin-valve thin-film magnetic element in which an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer, one each, are formed.
For the spin-valve thin-film magnetic element, a magnetic recording medium, such as a hard disk, travels in the Z direction in the drawing, and a fringing magnetic field from the magnetic recording medium is directed in the Y direction.
As shown in FIG. 35, the conventional spin-valve thin-film magnetic element includes a laminate 109 in which an underlayer 106, an antiferromagnetic layer 101, a pinned magnetic layer 102, a nonmagnetic conductive layer 103, a free magnetic layer 104, and a protective layer 107 are deposited in that order on a substrate; hard bias layers 105 formed at both sides of the laminate 109; and electrode layers 108 formed on the hard bias layers 105. The underlayer 106 is composed of tantalum (Ta) or the like, and the antiferromagnetic layer 101 is composed of an NiO alloy, an FeMn alloy, an NiMn alloy, or the like. The pinned magnetic layer 102 and the free magnetic layer 104, respectively, are composed of Co, an NiFe alloy, or the like. The nonmagnetic conductive layer 103 is composed of a copper (Cu) film, the hard bias layers 105 are composed of a cobalt-platinum (Coxe2x80x94Pt) alloy or the like, and the electrode layers 108 are composed of Ta, Au, Cr, W, or the like.
Since the pinned magnetic layer 102 is brought into contact with the antiferromagnetic layer 101, an exchange coupling magnetic field (exchange anisotropic magnetic field) is generated at the interface between the pinned magnetic layer 102 and the antiferromagnetic layer 101, and the magnetization direction of the pinned magnetic layer 102 is pinned, for example, in the Y direction.
Since the hard bias layers 105 are magnetized in the X1 direction in the drawing, the variable magnetization of the free magnetic layer 104 sandwiched between the hard bias layers 105 is aligned in the X1 direction. Thereby, the variable magnetization of the free magnetic layer 104 and the pinned magnetization of the pinned magnetic layer 102 are substantially orthogonal to each other.
In the spin-valve thin-film magnetic element, a sensing current is applied from one electrode layer 108 formed on one hard bias layer 105 to the pinned magnetic layer 102, the nonmagnetic conductive layer 103, and the free magnetic layer 104. A magnetic recording medium, such as a hard disk, travels in the Z direction in the drawing, and when a fringing magnetic field from the magnetic recording medium is applied in the Y direction, the magnetization direction of the free magnetic layer 104 is rotated from the X1 direction to the Y direction. At this stage, electrical resistance changes due to the relationship between the varied magnetization direction of the free magnetic layer 104 and the pinned magnetization direction of the pinned magnetic layer 102, which is referred to as the magnetoresistance (MR) effect, and the fringing magnetic field from the magnetic recording medium is detected by a voltage change based on the change in the electrical resistance.
The spin-valve thin-film magnetic element is of an abutted junction type in which the variable magnetization of the free magnetic layer 104 is firmly pinned by the hard bias layers 105 located at both sides of the free magnetic layer 104, improving the stability of the magnetization of the free magnetic layer 104.
The magnetization of the free magnetic layer 104 is usually aligned in the track width direction under the influence of the hard bias layers 105 which are formed at both sides of the free magnetic layer 104 and which are magnetized in the track width direction. However, the influence of the hard bias layers 105 is largest at both ends of the free magnetic layer 104, and the influence decreases toward the center of the free magnetic layer 104.
FIGS. 36 and 37 are graphs showing the output profiles in the track width direction of the spin-valve thin-film magnetic element shown in FIG. 35.
The read output of the spin-valve thin-film magnetic element has a profile in the read track width direction (in the X1 direction shown in FIG. 35), and the midsection of the laminate 109 is a sensitive region 109a which substantially contributes to reading of the recorded magnetic field from the magnetic recording medium and which has a read output sufficiently high for exhibiting a magnetoresistance effect. The sensitive region 109a corresponds to the read track width Tw. On the other hand, regions at both sides of the sensitive region 109a in the laminate 109 are insensitive regions 109b having a low read output insufficient for substantially contributing to reading of the recorded magnetic field from the magnetic recording medium.
The sensitive region 109a and the insensitive regions 109b in the laminate 109 are determined by a microtrack profile method which will be described below.
In such a spin-valve thin-film magnetic element, instability in output is preferably low.
With increasing demands for improving recording density of magnetic recording onto medium, there are strong requirements for narrowing of a read track width to 1 xcexcm or less, and further to 0.5 xcexcm or less, and particularly to 0.4 xcexcm or less as well as for prevention of reduction in output.
However, in the abutted junction type spin-valve thin-film magnetic element, when the track width is narrowed, the read output is decreased.
The read output profile described above is caused by the fact that insensitive regions 104b of the free magnetic layer 104 which are nearer to the hard bias layers 105 are more strongly influenced by the magnetic field from the hard bias layers 105 and the variable magnetization of the free magnetic layer 104 is more firmly pinned compared to a sensitive region 104a in the midsection of the free magnetic layer 104 corresponding to the sensitive region 109a. That is, the influence of the hard bias layers 105 is largest at both ends of the free magnetic layer 104 and the influence decreases toward the center of the free magnetic layer 104, i.e., the influence decreases as the distance from the hard bias layers 105 is increased, and thus the insensitive regions 104b occur.
Herein, the insensitive regions 104b refer to the regions in which rotation of the variable magnetization of the free magnetic layer 104 is blunted, and do not correspond to a difference between the physical track width and the optical track width.
Therefore, since the width in the track width direction of the insensitive region 104b does not depend on the width in the track width direction of the spin-valve thin-film magnetic element, even when the width in the track width direction of the entire laminate 109 is decreased for the purpose of track narrowing, the width in the track width direction of the insensitive region 104b is not changed or narrowed.
Consequently, when the track width is narrowed to meet track narrowing, it seems as if the sensitive region 104a was decreased, and the read output profile curves corresponding to the insensitive regions 104b move toward the center in the track width direction.
In particular, when the read track width is set at 0.4 xcexcm or less to meet further track narrowing, it seems as if the sensitive region 104a disappeared and the insensitive region 104b covered the entirety of the free magnetic layer in the track width direction, and as shown in FIG. 37, the read output, i.e., the maximum of the read output, is decreased.
On the other hand, in the spin-valve thin-film magnetic element having a multilayered structure including metallic films, upper and lower surfaces thereof and a back side in the height direction are covered by an insulating film (gap film), and a front side (ABS) opposite to the back side is exposed to outside, and thus, tensile stress is applied in the height direction to the central section of the free magnetic layer in the spin-valve thin-film magnetic element.
Consequently, when the read track width is set at approximately 1 xcexcm or more, as described above, since the influence of the hard bias layers 105 is largest at both ends of the free magnetic layer 104, and the influence decreases toward the center of the free magnetic layer 104, in particular, the central section of the free magnetic layer 104 is greatly influenced by a uniaxial anisotropic magnetic field due to an inverse magnetostrictive effect determined by the stress applied to the free magnetic layer 104 and the magnetostriction.
As described above, since tensile stress is applied to the central section of the free magnetic layer 104, when the magnetostriction of the free magnetic layer 104 is positive and as its value is increased, easy magnetization rotation in the height direction due to the inverse magnetostrictive effect is increased and the height direction becomes the easy magnetization axis direction. In such a state, the central section of the free magnetic layer 104 is easily magnetized in the height direction, resulting in Barkhausen noise.
In other words, when magnetostriction occurs in the free magnetic layer 104, magnetic hysteresis may occur, and as shown in FIG. 38, the single-domain alignment of the free magnetic layer 104 is disturbed as if domain walls 104c are formed in the free magnetic layer 104, and the magnetization becomes nonuniform. Thus, Barkhausen noise, etc., may easily occur, resulting in instability leading to inaccurate processing of signals from the magnetic recording medium.
For example, when a hysteresis occurs, a baseline shift occurs as shown in FIG. 40 and the regenerated waveform loses symmetry, in contrast with the regenerated waveform shown in FIG. 39 when there is no hysteresis. FIGS. 39 and 40 are graphs showing regenerated waveforms of spin-valve thin-film magnetic elements.
Accordingly, with respect to spin-valve thin-film magnetic elements, there have been attempts to reduce the influence of magnetostriction.
Furthermore, along with the fundamental need for track narrowing of spin-valve thin-film magnetic elements, there are also demands for an improvement in output characteristics and an improvement in sensitivity.
Objects of the present invention are to improve output characteristics of a spin-valve thin-film magnetic element when the track width is narrowed, to improve stability in regenerated waveform in a spin-valve thin-film magnetic element, to control magnetostriction in a spin-valve thin-film magnetic element, and to provide a thin-film magnetic head provided with such a spin-valve thin-film magnetic element.
In one aspect of the present invention, a spin-valve thin-film magnetic element includes a substrate; an antiferromagnetic layer; a pinned magnetic layer in contact with the antiferromagnetic layer, the magnetization direction of the pinned magnetic layer being pinned by an exchange coupling magnetic field with the antiferromagnetic layer; a free magnetic layer formed in contact with the pinned magnetic layer with a nonmagnetic conductive layer therebetween, the magnetization direction of the free magnetic layer being aligned in a direction substantially orthogonal to the magnetization direction of the pinned magnetic layer; a pair of hard bias layers for aligning the magnetization direction of the free magnetic layer in the direction substantially orthogonal to the magnetization direction of the pinned magnetic layer; and a pair of electrode layers for applying a sensing current to the pinned magnetic layer, the nonmagnetic conductive layer, and the free magnetic layer. The magnetic read track width Tw is set at 0.4 xcexcm or less. At least a part of the free magnetic layer is composed of an NiFe alloy, and the Ni content CNi is in the range of 70.2 to 89.9 atomic percent.
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 1 as point (Tw, CNi), are within the range obtained by linking point A1 (0.4, 89.9), point B1 (0.35, 89), point C1 (0.3, 87.7), point D1 (0.25, 86.5), point E1 (0.22, 84.9), point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), point S1 (0.20, 70.2), point T1 (0.22, 70.2), point U1 (0.25, 71.5), point V1 (0.3, 73.6), point W1 (0.35, 75.6), and point X1 (0.4, 77.3).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 2 as point (Tw, CNi), are within the range obtained by linking point A2 (0.4, 83.7), point B2 (0.35, 83.9), point C2 (0.3, 83.5), point D2 (0.25, 83), point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), point T2 (0.22, 73.6), point U2 (0.25, 74), point V2 (0.3, 75.6), point W2 (0.35, 76.5), and point X2 (0.4, 77.3).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 3 as point (Tw, CNi), are within the range obtained by linking point B1 (0.35, 89), point C1 (0.3, 87.7), point D1 (0.25, 86.5), point E1 (0.22, 84.9), point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), point S1 (0.20, 70.2), point T1 (0.22, 70.2), point U1 (0.25, 71.5), point V1 (0.3, 73.6), and point W1 (0.35, 75.6).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 4 as point (Tw, CNi), are within the range obtained by linking point B2 (0.35, 83.9), point C2 (0.3, 83.5), point D2 (0.25, 83), point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), point T2 (0.22, 73.6), point U2 (0.25, 74), point V2 (0.3, 75.6), and point W2 (0.35, 76.5).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 5 as point (Tw, CNi), are within the range obtained by linking point C1 (0.3, 87.7), point D1 (0.25, 86.5), point E1 (0.22, 84.9), point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), point S1 (0.20, 70.2), point T1 (0.22, 70.2), point U1 (0.25, 71.5), and point V1 (0.3, 73.6).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 6 as point (Tw, CNi), are within the range obtained by linking point C2 (0.3, 83.5), point D2 (0.25, 83), point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), point T2 (0.22, 73.6), point U2 (0.25, 74), and point V2 (0.3, 75.6).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 7 as point (Tw, CNi), are within the range obtained by linking point D1 (0.25, 86.5), point E1 (0.22, 84.9), point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), pint O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), point S1 (0.20, 70.2), point T1 (0.22, 70.2), and point U1 (0.25, 71.5).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 8 as point (Tw, CNi), are within the range obtained by linking point D2 (0.25, 83), point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), point T2 (0.22, 73.6), and point U2 (0.25, 74).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 9 as point (Tw, CNi), are within the range obtained by linking point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), and point S1 (0.20, 70.2).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 10 as point (Tw, CNi), are within the range obtained by linking point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), and point T2 (0.22, 73.6).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 11 as point (Tw, CNi), are within the range obtained by linking point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1(0.17, 70.2), point Q1 (0.18, 70.2), and point R1 (0.19, 70.2).
Preferably, the magnetic read track width Tw (∥m) and the Ni content CNi (at. %), which are shown in accompanying FIG. 12 as point (Tw, CNi), are within the range obtained by linking point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), and point S2 (0.20, 72.5).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 13 as point (Tw, CNi), are within the range obtained by linking point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), and point Q1 (0.18, 70.2).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 14 as point (Tw, CNi), are within the range obtained by linking point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), and point R2 (0.19, 72).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 15 as point (Tw, CNi), are within the range obtained by linking point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), and point P1 (0.17, 70.2).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 16 as point (Tw, CNi), are within the range obtained by linking point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), and point Q2 (0.18, 71.7).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 17 as point (Tw, CNi), are within the range obtained by linking point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), and point O1 (0.15, 70.2).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 18 as point (Tw, CNi), are within the range obtained by linking point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), and point O2 (0.15, 70.6).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 19 as point (Tw, CNi), are within the range obtained by linking point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), and point N1 (0.13, 70.2).
Preferably, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in accompanying FIG. 20 as point (Tw, CNi), are within the range obtained by linking point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), and point N2 (0.13, 70.6).
In the spin-valve thin-film magnetic element of the present invention, preferably, the antiferromagnetic layer, the pinned magnetic layer, the nonmagnetic conductive layer, and the free magnetic layer are deposited in that order on the substrate.
Preferably, the antiferromagnetic layer is composed of one of an Xxe2x80x94Mn alloy and a Ptxe2x80x94Mnxe2x80x94Xxe2x80x2 alloy, where X is one element selected from the group consisting of Pt, Pd, Ir, Rh, Ru, and Os, and Xxe2x80x2 is at least one element selected from the group consisting of Pd, Cr, Ru, Ni, Ir, Rh, Os, Au, Ag, Ne, Ar, Xe, and Kr.
In the spin-valve thin-film magnetic element of the present invention, at least one of the pinned magnetic layer and the free magnetic layer may be divided into two sublayers by a nonmagnetic intermediate layer to produce a ferrimagnetic state in which the magnetization directions of the sublayers are antiparallel to each other.
In the spin-valve thin-film magnetic element of the present invention, preferably, the ratio of the width in the read track width direction of the free magnetic layer to the height in the element height direction of the free magnetic layer is approximately 1:1 to 3:2.
In another aspect of the present invention, a thin-film magnetic head is provided with the spin-valve thin-film magnetic element described above.
Generally, with respect to a spin-valve thin-film magnetic element having a track width of approximately 1 xcexcm, in a laminate, for example, formed by depositing an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer, the entire laminate does not exhibit a magnetoresistance effect. Only the central region thereof has superior read sensitivity, and the central region substantially exhibits the magnetoresistance effect.
The region having superior read sensitivity is referred to as a sensitive region, and regions having poor read sensitivity at both sides of the sensitive region are referred to as insensitive regions. The sensitive region and the insensitive regions in the laminate are determined by a microtrack profile method.
The microtrack profile method will be described below with reference to FIG. 41.
As shown in FIG. 41, a conventional spin-valve thin-film magnetic element including a laminate exhibiting a magnetoresistance effect, hard bias layers disposed at both sides of the laminate, and electrode layers disposed on the hard bias layers, in which magnetostriction is negligible, is formed on a substrate.
Next, a width A of the upper surface of the laminate is determined by an optical microscope or a scanning electron microscope. The width A is defined as a track width Tw determined by an optical method (hereinafter referred to as an optical track width O-Tw), and it is set at approximately 1 xcexcm.
A predetermined signal, as a microtrack, is recorded on a magnetic recording medium, and by moving the spin-valve thin-film magnetic element over the microtrack in the track width direction, the relationship between the width A of the laminate and the read output is measured. Alternatively, the magnetic recording medium provided with the microtrack may be moved over the spin-valve thin-film magnetic element in the track width direction to measure the relationship between the width A of the laminate and the read output. A measurement result is shown in the bottom of FIG. 41.
According to the measurement result, the read output is high in the central region of the laminate, and is low in the side regions of the laminate. As is obvious from this result, the central region exhibits a satisfactory magnetoresistance effect and contributes to reading, while the magnetoresistance effect is deteriorated in the side regions, resulting in poor read output, and contribution to reading is low.
Generally, as shown in FIG. 41, a region corresponding to a width B of the upper surface of the laminate in which a read output of 50% or more relative to the maximum read output is generated is defined as a sensitive region, and regions, each corresponding to a width C of the upper surface of the laminate in which a read output below 50% relative to the maximum read output is generated, are defined as insensitive regions. Herein, the insensitive regions mean the regions in which rotation of the variable magnetization of a free magnetic layer is blunted due to a magnetic field from the hard bias layers, and do not correspond to a difference between the physical track width and the optical track width.
The spin-valve thin-film magnetic element of the present invention includes a laminate including an antiferromagnetic layer; a pinned magnetic layer in contact with the antiferromagnetic layer, the magnetization direction of the pinned magnetic layer being pinned by an exchange coupling magnetic field with the antiferromagnetic layer; and a free magnetic layer formed in contact with the pinned magnetic layer with a nonmagnetic conductive layer therebetween, the magnetization direction of the free magnetic layer being aligned in a direction substantially orthogonal to the magnetization direction of the pinned magnetic layer. At both sides of the laminate in the track width direction, hard bias layers for aligning the magnetization direction of the free magnetic layer in the direction substantially orthogonal to the magnetization direction of the pinned magnetic layer and a pair of electrode layers for applying a sensing current to the vicinity of the free magnetic layer are disposed. The magnetic read track width Tw defined by the microtrack profile method is set at 0.4 xcexcm or less. At least a part of the free magnetic layer is composed of an NiFe alloy, and the Ni content CNi is in the range of 70.2 to 89.9 atomic percent. Consequently, it is possible to improve the read output of the spin-valve thin-film magnetic element decreased due to track narrowing.
In the spin-valve thin-film magnetic element, when the track width is 0.4 xcexcm or less, the read output, as it is, is lower compared to the case in which the track width is set at approximately 1 xcexcm. However, in the present invention, in order to improve the read output by the inverse magnetostrictive effect, the composition of the free magnetic layer is specified.
The relationship between magnetostriction and the output of the spin-valve thin-film magnetic element will now be described.
In general, stress applied to a film planarly formed is substantially isotropic in the in-plane direction. However, in a film in which a part thereof is open by cutting, such as in an ABS, the stress distribution is anisotropic in the in-plane direction. For example, in such a case, tensile stress is applied anisotropically to the free magnetic layer in the element height direction (stripe height direction).
When the magnetostriction of a magnetic member, i.e., the free magnetic layer, is zero, magnetostriction does not occur when the free magnetic layer is magnetized. Therefore, the magnetic anisotropy induced by the magnetostriction of the free magnetic layer is isotropic.
However, when the magnetostriction is set to be positive, i.e., elongation occurs in the magnetized direction, the magnetization is easily oriented in the direction of the tensile stress applied due to the inverse magnetostriction, and magnetic anisotropy is exhibited. That is, in the free magnetic layer to which the tensile stress is applied, the direction of the tensile stress can be set as an easy magnetization axis.
Although the magnetization of the free magnetic layer is pinned in the track width direction by the magnetic field from the hard bias layers, since the free magnetic layer has magnetic anisotropy in the element height direction, the magnetization is relatively easily rotated in the easy magnetization axis direction, i.e., in the element height direction, against (overcoming) the magnetic field from the hard bias layers.
Consequently, in the spin-valve thin-film magnetic element, since a change in resistance is easily caused by the magnetoresistance effect exhibited because of the rotation of the variable magnetization direction of the free magnetic layer relative to the pinned magnetization direction of the pinned magnetic layer, an increase in read output can be expected.
On the other hand, in the spin-valve thin-film magnetic element in which the track width is set at 0.4 xcexcm or less as described above, when the magnetization of the free magnetic layer is aligned in the track width direction under the influence of the hard bias layers, since the free magnetic layer does not have a region which is sufficiently distant from the hard bias layers for producing a sensitive region, significant variations in the influence of the hard bias layers on the free magnetic layer in the track width direction are avoided compared to the case in which the track width is wider than 0.4 xcexcm.
Consequently, by setting the Ni content CNi in the NiFe alloy constituting the free magnetic layer as described above, it is possible to set the magnetostriction xcexs of the free magnetic layer in the element height direction in the range of xe2x88x927.0xc3x9710xe2x88x926 to 2.0xc3x9710xe2x88x925, and it is also possible to prevent the easy magnetization rotation of the variable magnetization of the free magnetic layer from having a distribution in the track width direction so as to produce domain walls, resulting in an unstable domain, in comparison with the case in which the track width is wide.
Therefore, the free magnetic layer does not have regions with varied sensitivity in the track width direction, and single-domain alignment of the free magnetic layer is not obstructed by domain walls, thus nonuniform magnetization is prevented, and it is possible to avoid Barkhausen noise, etc., which results in instability wherein signals from a magnetic recording medium are inaccurately processed in the spin-valve thin-film magnetic element.
In the present invention, if the magnetic read track width Tw is more than 0.4 xcexcm, as described above, domain walls may be produced in the free magnetic layer, and if the Ni content CNi is less than 70.2 atomic percent, the coercive force from the hard bias layers in the free magnetic layer is approximately 400 A/m or more, thus soft magnetic properties of the free magnetic layer are degraded. If the Ni content CNi is more than 89.9 atomic percent, read output in a low frequency band of approximately 10 to 20 MHz is decreased to less than the practical lower limit of 1.2 mV.
When the Ni content CNi (at. %) is set as described above, if the magnetostriction xcexs of the free magnetic layer is less than xe2x88x927.0xc3x9710xe2x88x926, the variable magnetization of the free magnetic layer is pinned more firmly than necessary and is not rotated with high sensitivity relative to an applied external magnetic field, and read output in a low frequency band of approximately 10 to 20 MHz is decreased to less than the practical lower limit of 1.2 mV. If the magnetostriction xcexs is more than 2.0xc3x9710xe2x88x925, the coercive force in the free magnetic layer is approximately 400 A/m, degrading soft magnetic properties of the free magnetic layer.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 1 as point (Tw, CNi), may be set within the range obtained by linking point A1 (0.4, 89.9), point B1 (0.35, 89), point C1 (0.3, 87.7), point D1 (0.25, 86.5), point E1 (0.22, 84.9), point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), point S1 (0.20, 70.2), point T1 (0.22, 70.2), point U1 (0.25, 71.5), point V1 (0.3, 73.6), point W1 (0.35, 75.6), and point X1 (0.4, 77.3). Consequently, it is possible to set the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926) of the free magnetic layer, which are shown in FIG. 42 as point (Tw, xcexs), within the range obtained by linking point SA1 (0.4, 6), point SB1 (0.35, 8), point SC1 (0.3, 12.5), point SD1 (0.25, 18), point SE1 (0.23, 20), point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), point SQ1 (0.2, xe2x88x920.7), point SR1 (0.22, xe2x88x922), point SS1 (0.25, xe2x88x923), point ST1 (0.3, xe2x88x925), point SU1 (0.35, xe2x88x926.3), and point SV1 (0.4, xe2x88x927).
FIGS. 42 and 43 are graphs showing the ranges of the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926) of the free magnetic layer in the present invention.
If the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %) are outside of the range described above, problems as described below may be caused.
1. If the magnetic read track width Tw is set to the right of point A1 and point X1 in FIG. 1, as described above, domain walls may be produced in the free magnetic layer, resulting in Barkhausen noise, etc., which causes instability.
2. If the magnetic read track width Tw (xcexcm) and the Ni content CNi are above the polygonal line obtained by linking point A1, point B1, point C1, point D1, point E1, point F1, point G1, point H1, point I1, point J1, point K1, and point L1, the variable magnetization of the free magnetic layer is more firmly pinned than necessary by the hard bias layers and is not rotated with high sensitivity relative to an applied external magnetic field, and read output in a low frequency band of approximately 10 to 20 MHz is decreased to less than the practical lower limit of 1.2 mV.
3. If the Ni content CNi is below point M1, point N1, point O1, point P1, point Q1, point R1, point S1, and point T1, the coercive force in the free magnetic layer is increased to approximately 400 A/m or more, and the soft magnetic properties of the free magnetic layer are degraded, resulting in an increase in distortion of regenerated waveforms and instability.
4. If the magnetic read track width Tw (xcexcm) and the Ni content CNi are below the polygonal line obtained by linking point T1, point U1, point V1, point W1, and point X1, read output in a low frequency band of approximately 10 to 20 MHz is increased to more than the practical upper limit of 2.0 mV, and instability in regenerated waveform may be increased.
When the track width is less than 0.1 xcexcm, since it is difficult to obtain output even if the magnetostriction is increased as in the case of the present invention, it is unlikely that the hard bias system itself in which the magnetization direction of the free magnetic layer is aligned by the hard bias layers will be used. Therefore, in the present invention, the track width is set at 0.1 xcexcm or more.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 2 as point (Tw, CNi), may be within the range obtained by linking point A2 (0.4, 83.7), point B2 (0.35, 83.9), point C2 (0.3, 83.5), point D2 (0.25, 83), point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), point T2 (0.22, 73.6), point U2 (0.25, 74), point V2 (0.3, 75.6), point W2 (0.35, 76.5), and point X2 (0.4, 77.3). Consequently, it is possible to set the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926) of the free magnetic layer, which are shown in FIG. 43 as point (Tw, xcexs), within the range obtained by linking point SA2 (0.4, 6), point SB2 (0.35, 6), point SC2 (0.3, 7.5), point SD2 (0.25, 10.5), point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), point SR2 (0.23, xe2x88x920.5), point SS2 (0.25, xe2x88x921), point ST2 (0.3, xe2x88x921.5), point SU2 (0.35, xe2x88x921.6), and point SV2 (0.4, xe2x88x921.5).
If the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %) are outside of the range described above, problems as described below may be caused.
1. If the magnetic read track width Tw is set to the right side of the line obtained by linking point A2 and point X2 in FIG. 2, as described above, domain walls may be formed in the free magnetic layer, resulting in Barkhausen noise, etc., which causes instability.
2. If the magnetic read track width Tw (xcexcm) and the Ni content CNi are above the polygonal line obtained by linking point A2, point B2, point C2, point D2, point E2, point F2, point G2, point H2, point J2, point K2, and point L2, the variable magnetization of the free magnetic layer is more firmly pinned than necessary by the hard bias layers and is not rotated with high sensitivity relative to an applied external magnetic field, and read output in a low frequency band of approximately 10 to 20 MHz is decreased to less than the practical lower limit of 1.2 mV.
Furthermore, within the range delimited by the polygonal line obtained by linking point A2 to point L2, it is not necessary to decrease the product of the remanence and the thickness of the hard bias layers for stabilizing the variable magnetization of the free magnetic layer to less than the value required for more reliably avoiding the instability in regenerated waveform as the track width is decreased.
3. If the Ni content CNi is below point M2, point N2, and point O2, the coercive force in the free magnetic layer is increased to approximately 400 A/m or more, and the soft magnetic properties of the free magnetic layer are degraded, resulting in an increase in distortion of regenerated waveforms and instability.
4. If the magnetic read track width Tw (xcexcm) and the Ni content CNi are below the polygonal line obtained by linking point O2, point Q2, point R2, point S2, point T2, point U2, point V2, point W2, and point X2, read output in a low frequency band of approximately 10 to 20 MHz is increased to more than the practical upper limit of 2.0 mV, and instability in regenerated waveform may be increased.
Furthermore, by setting the range inside point E2 and point V2, the product of the remanence and the thickness of the hard bias layers for stabilizing the variable magnetization of the free magnetic layer may become small as the track width is decreased, and magnetic read track width can be controlled more precisely.
It is known that the magnetostriction of an NiFe alloy film in a bulk solid state is greatly influenced by the composition of the NiFe alloy film. It is also known that, if nonmagnetic atoms are added to an NiFe alloy in a bulk solid state, magnetostriction changes depending on the amount of the nonmagnetic atoms added and the type of the nonmagnetic atoms.
As is the case with the free magnetic layer in the spin-valve thin-film magnetic element, when an NiFe alloy film or a laminate including an NiFe alloy film and a CoFe alloy film is formed at a small thickness of several tens of atoms, and a nonmagnetic film is formed on the upper and the lower surface thereof, since nonmagnetic atoms (Ta and Cu) and ferromagnetic atoms (Ni and Fe) are directly brought into contact with each other, the magnetostriction of the ferromagnetic atoms of the NiFe alloy film directly in contact with the nonmagnetic atoms changes. The change in magnetostriction between when the nonmagnetic atoms comprise Ta and when the nonmagnetic atoms comprise Cu is different. Therefore, in each of a top-type spin-valve thin-film magnetic element (in which a PtMn layer is arranged on the top), a bottom-type spin-valve thin-film magnetic element (in which a PtMn layer is arranged on the bottom), and a dual spin-valve thin-film magnetic element, it is possible to define the compositional range of an NiFe alloy film, which constitutes at least a part of the free magnetic layer, required for optimizing the magnetostriction of the free magnetic layer.
By annealing the spin-valve thin-film magnetic element, a thermal diffusion layer is formed at the interface between the NiFe alloy film of the free magnetic layer and the nonmagnetic film composed of Ta, Cu, or the like, and more ferromagnetic atoms in the NiFe alloy film are brought into contact with the nonmagnetic atoms disposed above and below. Although the thickness of the thermal diffusion layer between the NiFe alloy film and the nonmagnetic film depends on the annealing temperature, the annealing time, the type of the nonmagnetic film, and whether the nonmagnetic film is disposed above or below the NiFe alloy film, it does not substantially depend on the thickness of the NiFe alloy film, and the proportion of the thermal diffusion layer in the NiFe alloy film is increased as the thickness of the NiFe alloy film is decreased. Consequently, as the thickness of the NiFe alloy film is decreased, the influence of the magnetostriction changed by the formation of the thermal diffusion layer is increased. Therefore, if the thickness of the NiFe alloy film is changed, the magnetostriction changes. For the same reason, if annealing treatment is performed, the magnetostriction changes.
Even if the NiFe alloy films have the same composition and thickness, and are annealed under the same conditions, since the nonmagnetic materials sandwiching the NiFe alloy films of the top-type or bottom-type spin-valve thin-film magnetic element and of the dual-type spin-valve thin-film magnetic element are different, the NiFe alloy films, which constitute at least some of the free magnetic layers required for optimizing the magnetostriction of the free magnetic layers, have different compositional ranges. On the other hand, with respect to the top-type spin-valve film and the bottom-type spin-valve film, although the same nonmagnetic material is used for the films formed above and below the NiFe alloy films, since the deposition orders are the opposite of each other, different lattice mismatch (coherency) occurs at the interface. Thereby, the proportion of the ferromagnetic atoms and nonmagnetic atoms directly in contact with each other and the contact state are different, and the thermal diffusivity at the interface is different. Therefore, the compositional range of the NiFe alloy film, which constitutes at least a part of the free magnetic layer, required for optimizing the magnetostriction of the free magnetic layer is different.
In the present invention, in consideration of the above situation, the magnetic read track width Tw (xcexcm) and the Ni content CNi in the NiFe alloy constituting at least a part of the free magnetic layer are defined.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 3 as point (Tw, CNi), may be within the range obtained by linking point B1 (0.35, 89), point C1 (0.3, 87.7), point D1 (0.25, 86.5), point E1 (0.22, 84.9), point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), point S1 (0.20, 70.2), point T1 (0.22, 70.2), point U1 (0.25, 71.5), point V1 (0.3, 73.6), and point W1 (0.35, 75.6). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 42. Consequently, in particular, in a magnetic head with a read track width of 0.35 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 4 as point (Tw, CNi), may be within the range obtained by linking point B2 (0.35, 83.9), point C2 (0.3, 83.5), point D2 (0.25, 83), point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), point T2 (0.22, 73.6), point U2 (0.25, 74), point V2 (0.3, 75.6), and point W2 (0.35, 76.5). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 43. Consequently, in particular, in a magnetic head with a read track width of 0.35 xcexcm or less, distortion of regenerated waveforms and instability are effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 5 as point (Tw, CNi), may be within the range obtained by linking point C1 (0.3, 87.7), point D1 (0.25, 86.5), point E1 (0.22, 84.9), point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), point S1 (0.20, 70.2), point T1 (0.22, 70.2), point U1 (0.25, 71.5), and point V1 (0.3, 73.6). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 42. Consequently, in particular, in a magnetic head with a read track width of 0.3 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 6 as point (Tw, CNi), may be within the range obtained by linking point C2 (0.3, 83.5), point D2 (0.25, 83), point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), point T2 (0.22, 73.6), point U2 (0.25, 74), and point V2 (0.3, 75.6). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 43. Consequently, in particular, in a magnetic head with a read track width of 0.3 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 7 as point (Tw, CNi), may be within the range obtained by linking point D1 (0.25, 86.5), point E1 (0.22, 84.9), point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), point S1 (0.20, 70.2), point T1 (0.22, 70.2), and point U1 (0.25, 71.5). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 42. Consequently, in particular, in a magnetic head with a read track width of 0.25 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 8 as point (Tw, CNi), may be within the range obtained by linking point D2 (0.25, 83), point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), point T2 (0.22, 73.6), and point U2 (0.25, 74). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 43. Consequently, in particular, in a magnetic head with a read track width of 0.25 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 9 as point (Tw, CNi), may be within the range obtained by linking point F1 (0.20, 83), point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1(0.17, 70.2), point Q1 (0.18, 70.2), point R1 (0.19, 70.2), and point S1 (0.20, 70.2). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 42. Consequently, in particular, in a magnetic head with a read track width of 0.25 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 10 as point (Tw, CNi), may be within the range obtained by linking point E2 (0.22, 82.9), point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), point S2 (0.20, 72.5), and point T2 (0.22, 73.6). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 43. Consequently, in particular, in a magnetic head with a read track width of 0.22 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 11 as point (Tw, CNi), may be within the range obtained by linking point G1 (0.19, 82.5), point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), point Q1 (0.18, 70.2), and point R1 (0.19, 70.2). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 42. Consequently, in particular, in a magnetic head with a read track width of 0.19 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 12 as point (Tw, CNi), may be within the range obtained by linking point F2 (0.20, 81.5), point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), point R2 (0.19, 72), and point S2 (0.20, 72.5). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 43. Consequently, in particular, in a magnetic head with a read track width of 0.2 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 13 as point (Tw, CNi), may be within the range obtained by linking point H1 (0.18, 81), point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), point P1 (0.17, 70.2), and point Q1 (0.18, 70.2). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 42. Consequently, in particular, in a magnetic head with a read track width of 0.18 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 14 as point (Tw, CNi), may be within the range obtained by linking point G2 (0.19, 81), point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), point Q2 (0.18, 71.7), and point R2 (0.19, 72). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 43. Consequently, in particular, in a magnetic head with a read track width of 0.19 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 15 as point (Tw, CNi), may be within the range obtained by linking point I1 (0.17, 80.5), point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), point O1 (0.15, 70.2), and point P1 (0.17, 70.2). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 42. Consequently, in particular, in a magnetic head with a read track width of 0.17 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 16 as point (Tw, CNi), may be within the range obtained by linking point H2 (0.18, 80), point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), point O2 (0.15, 70.6), and point Q2 (0.18, 71.7). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 43. Consequently, in particular, in a magnetic head with a read track width of 0.18 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 17 as point (Tw, CNi), may be within the range obtained by linking point J1 (0.15, 77.3), point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), point N1 (0.13, 70.2), and point O1 (0.15, 70.2). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 42. Consequently, in particular, in a magnetic head with a read track width of 0.15 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 18 as point (Tw, CNi) may be within the range obtained by linking point J2 (0.15, 78.4), point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), point N2 (0.13, 70.6), and point O2 (0.15, 70.6). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 43. Consequently, in particular, in a magnetic head with a read track width of 0.15 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 19 as point (Tw, CNi), may be within the range obtained by linking point K1 (0.13, 76.8), point L1 (0.1, 75), point M1 (0.1, 70.2), and point N1 (0.13, 70.2). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 42. Consequently, in particular, in a magnetic head with a read track width of 0.13 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the Ni content CNi (at. %), which are shown in FIG. 20 as point (Tw, CNi), may be within the range obtained by linking point K2 (0.13, 76.5), point L2 (0.1, 75), point M2 (0.1, 70.6), and point N2 (0.13, 70.6). If the above range is satisfied, it is possible to set the magnetostriction xcexs of the free magnetic layer within the range defined by the corresponding track width range in FIG. 43. Consequently, in particular, in a magnetic head with a read track width of 0.125 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In another aspect of the present invention, a spin-valve thin-film magnetic element includes a substrate; an antiferromagnetic layer; a pinned magnetic layer in contact with the antiferromagnetic layer, the magnetization direction of the pinned magnetic layer being pinned by an exchange coupling magnetic field with the antiferromagnetic layer; a free magnetic layer formed in contact with the pinned magnetic layer with a nonmagnetic conductive layer therebetween, the magnetization direction of the free magnetic layer being aligned in a direction substantially orthogonal to the magnetization direction of the pinned magnetic layer; a pair of hard bias layers for aligning the magnetization direction of the free magnetic layer in the direction substantially orthogonal to the magnetization direction of the pinned magnetic layer; and a pair of electrode layers for applying a sensing current to the pinned magnetic layer, the nonmagnetic conductive layer, and the free magnetic layer. The magnetic read track width Tw is set at 0.4 xcexcm or less. The magnetostriction xcexs of the free magnetic layer is in the range of xe2x88x927.0xc3x9710xe2x88x926 to 2.0xc3x9710xe2x88x925.
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), are within the range obtained by linking point SA1 (0.4, 6), point SB1 (0.35, 8), point SC1 (0.3, 12.5), point SD1 (0.25, 18), point SE1 (0.23, 20), point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), point SQ1 (0.2, xe2x88x920.7), point SR1 (0.22, xe2x88x922), point SS1 (0.25, xe2x88x923), point ST1 (0.3, xe2x88x925), point SU1 (0.35, xe2x88x926.3), and point SV1 (0.4, xe2x88x927).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SA2 (0.4, 6), point SB2 (0.35, 6), point SC2 (0.3, 7.5), point SD2 (0.25, 10.5), point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), point SR2 (0.23, xe2x88x920.5), point SS2 (0.25, xe2x88x921), point ST2 (0.3, xe2x88x921.5), point SU2 (0.35, xe2x88x921.6), and point SV2 (0.4, xe2x88x921.5).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), are within the range obtained by linking point SB1 (0.35, 8), point SC1 (0.3, 12.5), point SD1 (0.25, 18), point SE1 (0.23, 20), point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), point SQ1 (0.2, xe2x88x920.7), point SR1 (0.22, xe2x88x922), point SS1 (0.25, xe2x88x923), point ST1 (0.3, xe2x88x925), and point SU1 (0.35, xe2x88x926.3).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SB2 (0.35, 6), point SC2 (0.3, 7.5), point SD2 (0.25, 10.5), point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), point SR2 (0.23, xe2x88x920.5), point SS2 (0.25, xe2x88x921), point ST2 (0.3, xe2x88x921.5), and point SU2 (0.35, xe2x88x921.6).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), are within the range obtained by linking point SC1 (0.3, 12.5), point SD1 (0.25, 18), point SE1 (0.23, 20), point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), point SQ1 (0.2, xe2x88x920.7), point SR1 (0.22, xe2x88x922), point SS1 (0.25, xe2x88x923), and point ST1 (0.3, xe2x88x925).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SC2 (0.3, 7.5), point SD2 (0.25, 10.5), point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), point SR2 (0.23, xe2x88x920.5), point SS2 (0.25, xe2x88x921), and point ST2 (0.3, xe2x88x921.5).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), are within the range obtained by linking point SD1 (0.25, 18), point SE1 (0.23, 20), point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), point SQ1 (0.2, xe2x88x920.7), point SR1 (0.22, xe2x88x922), and point SS1 (0.25, xe2x88x923).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SD2 (0.25, 10.5), point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), point SR2 (0.23, xe2x88x920.5), and point SS2 (0.25, xe2x88x921).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), are within the range obtained by linking point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), and point SQ1 (0.2, xe2x88x920.7).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), and point SQ2 (0.22, 0).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), are within the range obtained by linking point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), and point SP1 (0.19, 0).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), and point SP2 (0.2, 1).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), are within the range obtained by linking point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), and point SO1 (0.18, 1).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), and point SO2 (0.19, 1.2).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), are within the range obtained by linking point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), and point SN1 (0.17, 2).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), and point SN2 (0.18, 1.5).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), are within the range obtained by linking point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), and point SM1 (0.15, 3.5).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), and point SM2 (0.15, 3.5).
Preferably, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 43 as point (Tw, xcexs), are within the range obtained by linking point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), and point SX2 (0.13, 5).
In the spin-valve thin-film magnetic element of the present invention, preferably, the antiferromagnetic layer, the pinned magnetic layer, the nonmagnetic conductive layer, and the free magnetic layer are deposited in that order on the substrate.
Preferably, the antiferromagnetic layer is composed of one of an X-Mn alloy and a Ptxe2x80x94Mnxe2x80x94Xxe2x80x2 alloy, where X is one element selected from the group consisting of Pt, Pd, Ir, Rh, Ru, and Os, and Xxe2x80x2 is at least one element selected from the group consisting of Pd, Cr, Ru, Ni, Ir, Rh, Os, Au, Ag, Ne, Ar, Xe, and Kr.
In the spin-valve thin-film magnetic element of the present invention, at least one of the pinned magnetic layer and the free magnetic layer may be divided into two sublayers by a nonmagnetic intermediate layer to produce a ferrimagnetic state in which the magnetization directions of the sublayers are antiparallel to each other.
In another aspect of the present invention, a thin-film magnetic head is provided with the spin-valve thin-film magnetic element described above.
Generally, with respect to a spin-valve thin-film magnetic element having a track width of approximately 1 xcexcm, in a laminate, for example, formed by depositing an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer, the entire laminate does not exhibit a magnetoresistance effect. Only the central region thereof has superior read sensitivity, and the central region substantially exhibits the magnetoresistance effect.
The region having superior read sensitivity is referred to as a sensitive region, and regions having poor read sensitivity at both sides of the sensitive region are referred to as insensitive regions. The sensitive region and the insensitive regions in the laminate are determined by a microtrack profile method.
The microtrack profile method will be described below with reference to FIG. 41.
As shown in FIG. 41, a conventional spin-valve thin-film magnetic element including a laminate exhibiting a magnetoresistance effect, hard bias layers disposed at both sides of the laminate, and electrode layers disposed on the hard bias layers, in which magnetostriction is negligible, is formed on a substrate.
Next, a width A of the upper surface of the laminate is determined by an optical microscope or a scanning electron microscope. The width A is defined as a track width Tw determined by an optical method (hereinafter referred to as an optical track width O-Tw), and it is set at approximately 1 xcexcm.
A predetermined signal, as a microtrack, is recorded on a magnetic recording medium, and by moving the spin-valve thin-film magnetic element over the microtrack in the track width direction, the relationship between the width A of the laminate and the read output is measured. Alternatively, the magnetic recording medium provided with the microtrack may be moved over the spin-valve thin-film magnetic element in the track width direction to measure the relationship between the width A of the laminate and the read output. A measurement result is shown in the bottom of FIG. 41.
According to the measurement result, the read output is high in the central region of the laminate, and is low in the side regions of the laminate. As is obvious from this result, the central region exhibits a satisfactory magnetoresistance effect and contributes to reading, while the magnetoresistance effect is deteriorated in the side regions, resulting in poor read output, and contribution to reading is low.
Generally, as shown in FIG. 41, a region corresponding to a width B of the upper surface of the laminate in which a read output of 50% or more relative to the maximum read output is generated is defined as a sensitive region, and regions, each corresponding to a width C of the upper surface of the laminate in which a read output below 50% relative to the maximum read output is generated, are defined as insensitive regions. Herein, the insensitive regions mean the regions in which rotation of the variable magnetization of a free magnetic layer is blunted due to a magnetic field from the hard bias layers, and do not correspond to a difference between the physical track width and the optical track width.
The spin-valve thin-film magnetic element of the present invention includes a laminate including an antiferromagnetic layer; a pinned magnetic layer in contact with the antiferromagnetic layer, the magnetization direction of the pinned magnetic layer being pinned by an exchange coupling magnetic field with the antiferromagnetic layer; and a free magnetic layer formed in contact with the pinned magnetic layer with a nonmagnetic conductive layer therebetween, the magnetization direction of the free magnetic layer being aligned in a direction substantially orthogonal to the magnetization direction of the pinned magnetic layer. At both sides of the laminate in the track width direction, hard bias layers for aligning the magnetization direction of the free magnetic layer in the direction substantially orthogonal to the magnetization direction of the pinned magnetic layer and a pair of electrode layers for applying a sensing current to the vicinity of the free magnetic layer are disposed. The magnetic read track width Tw defined by the microtrack profile method is set at 0.4 xcexcm or less. The magnetostriction xcexs of the free magnetic layer is in the range of xe2x88x927.0xc3x9710xe2x88x926 to 2.0xc3x9710xe2x88x925. Consequently, it is possible to improve the read output of the spin-valve thin-film magnetic element decreased due to track narrowing.
Herein, the track width direction means a direction parallel to the surface facing a medium (ABS) when the spin-valve thin-film magnetic element is formed as a thin-film magnetic head and parallel to the in-plane direction of the individual layers in the laminate. The element height direction means a direction orthogonal to the surface facing the medium.
In the spin-valve thin-film magnetic element, when the track width is 0.4 xcexcm or less, the read output, as it is, is lower compared to the case in which the track width is set at approximately 1 xcexcm. However, in the present invention, the read output is improved by the inverse magnetostrictive effect.
The relationship between magnetostriction and the output of the spin-valve thin-film magnetic element will be described.
In general, stress applied to a film planarly formed is substantially isotropic in the in-plane direction. However, in a film in which a part thereof is open by cutting, such as in the ABS of the free magnetic layer, the stress distribution is anisotropic in the in-plane direction. For example, in such a case, tensile stress is applied anisotropically to the free magnetic layer in the element height direction (stripe height direction).
When the magnetostriction of a magnetic member, i.e., the free magnetic layer, is zero, magnetostriction does not occur when the free magnetic layer is magnetized. Therefore, the magnetic anisotropy induced by the magnetostriction of the free magnetic layer is isotropic.
However, when the magnetostriction is set to be positive, i.e., elongation occurs in the magnetized direction, the magnetization is easily oriented in the direction of the tensile stress applied due to the inverse magnetostriction, and magnetic anisotropy is exhibited. That is, in the free magnetic layer to which the tensile stress is applied, the direction of the tensile stress can be set as an easy magnetization axis.
Although the magnetization of the free magnetic layer is pinned in the track width direction by the magnetic field from the hard bias layers, since the free magnetic layer has magnetic anisotropy in the element height direction, the magnetization is relatively easily rotated in the easy magnetization axis direction, i.e., in the element height direction, against (overcoming) the magnetic field from the hard bias layers.
Consequently, in the spin-valve thin-film magnetic element, since a change in resistance is easily caused by the magnetoresistance effect exhibited due to the rotation of the variable magnetization direction of the free magnetic layer relative to the pinned magnetization direction of the pinned magnetic layer, an increase in read output can be expected.
On the other hand, in the spin-valve thin-film magnetic element in which the track width is set at 0.4 xcexcm or less as described above, when the magnetization of the free magnetic layer is aligned in the track width direction under the influence of the hard bias layers, since the free magnetic layer does not have a region which is sufficiently distant from the hard bias layers for producing a sensitive region, significant variations in the influence of the hard bias layers on the free magnetic layer in the track width direction are avoided compared to the case in which the track width is wider than 0.4 xcexcm.
Consequently, by setting the magnetostriction xcexs as described above, it is possible to prevent the easy magnetization rotation of the variable magnetization of the free magnetic layer from having a large distribution in the track width direction so as to produce domain walls, resulting in an unstable domain, in comparison with the case in which the track width is wide.
Therefore, the free magnetic layer does not have regions with varied sensitivity in the track width direction, and single-domain alignment of the free magnetic layer is not obstructed by domain walls, thus nonuniform magnetization is prevented, and it is possible to avoid Barkhausen noise, etc., which results in instability wherein signals from a magnetic recording medium are inaccurately processed in the spin-valve thin-film magnetic element.
In the present invention, if the magnetic read track width Tw is more than 0.4 xcexcm, as described above, domain walls may be produced in the free magnetic layer, and if the magnetostriction xcexs of the free magnetic layer is less than xe2x88x927.0xc3x9710xe2x88x926, the variable magnetization of the free magnetic layer is more firmly pinned than necessary by the hard bias layers and is not rotated with high sensitivity relative to an applied external magnetic field, and read output in a low frequency band of approximately 10 to 20 MHz is decreased to less than the practical lower limit of 1.2 mV. If the magnetostriction xcexs is more than 2.0xc3x9710xe2x88x925, the coercive force in the free magnetic layer is approximately 400 A/m or more, thus soft magnetic properties of the free magnetic layer are degraded.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in accompanying FIG. 42 as point (Tw, xcexs), may be within the range obtained by linking point SA1 (0.4, 6), point SB1 (0.35, 8), point SC1 (0.3, 12.5), point SD1 (0.25, 18), point SE1 (0.23, 20), point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), point SQ1 (0.2, xe2x88x920.7), point SR1 (0.22, xe2x88x922), point SS1 (0.25, xe2x88x923), point ST1 (0.3, xe2x88x925), point SU1 (0.35, xe2x88x926.3), and point SV1 (0.4, xe2x88x927). If the magnetic read track width Tw and the magnetostriction xcexs are outside of the range described above, problems as described below may be caused.
1. If the magnetic read track width Tw is set to the right of point SA1 and point SV1, as described above, domain walls may be produced in the free magnetic layer, resulting in Barkhausen noise, etc., which causes instability.
2. If the magnetic read track width Tw and the magnetostriction xcexs are above the polygonal line obtained by linking point SA1, point SB1, point SC1, point SD1, and point SE1, read output in a low frequency band of approximately 10 to 20 MHz is increased to more than the practical upper limit of 2.0 mV, and instability in regenerated waveform may be increased.
3. If the magnetostriction xcexs is above point SE1, point SF1, point SG1, point SH1, point SI1, point SJ1, and point SK1, the coercive force in the free magnetic layer is increased to approximately 400 A/m or more, and the soft magnetic properties of the free magnetic layer are degraded, resulting in an increase in distortion of regenerated waveforms and instability.
4. If the magnetic read track width Tw and the magnetostriction xcexs are below the polygonal line obtained by linking point SL1, point SM1, point SN1, point SO1, point SP1, point SQ1, point SR1, point SS1, point ST1, point SU1, and point SV1, the variable magnetization of the free magnetic layer is pinned more firmly than necessary and is not rotated with high sensitivity relative to an applied external magnetic field, and read output in a low frequency band of approximately 10 to 20 MHz is decreased to less than the practical lower limit of 1.2 mV.
Additionally, a track width of less than 0.1 xcexcm is excluded from the present invention because it is difficult to obtain an output even if the magnetostriction is positively increased, and it is unlikely that the hard bias system itself in which the magnetization direction of the free magnetic layer is aligned by the hard bias layers will be used.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 43 as point (Tw, xcexs), may be within the range obtained by linking point SA2 (0.4, 6), point SB2 (0.35, 6), point SC2 (0.3, 7.5), point SD2 (0.25, 10.5), point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), point SR2 (0.23, xe2x88x920.5), point SS2 (0.25, xe2x88x921), point ST2 (0.3, xe2x88x921.5), point SU2 (0.35, xe2x88x921.6), and point SV2 (0.4, xe2x88x921.5). If the magnetic read track width Tw and the magnetostriction xcexs are outside of the range described above, problems as described below may be caused.
1. If the magnetic read track width Tw is set to the right of point SA2 and point SV2, as described above, domain walls may be produced in the free magnetic layer, resulting in Barkhausen noise, etc., which causes instability.
2. If the magnetic read track width Tw and the magnetostriction xcexs are above the polygonal line obtained by linking point SA2, point SB2, point SC2, point SD2, and point SE2, point SF2, point SG2, point SH2, point SI2, point SJ2, and point SW2, read output in a low frequency band of approximately 10 to 20 MHz is increased to more than the practical upper limit of 2.0 mV, and instability in regenerated waveform may be increased.
Furthermore, within the range delimited by the polygonal line obtained by linking point SA2 to point SW2, the product of the remanence and the thickness of the hard bias layers for stabilizing the variable magnetization of the free magnetic layer can be decreased as the track width is decreased, which is more advantageous in view of controlling the magnetic read track width.
3. If the magnetostriction xcexs is above point SW2 and point SK2, the coercive force in the free magnetic layer is increased to approximately 400 A/m or more, and the soft magnetic properties of the free magnetic layer are degraded, resulting in an increase in distortion of regenerated waveforms and instability.
4. If the magnetic read track width Tw and the magnetostriction xcexs are below the polygonal line obtained by linking point SL2, point SX2, point SM2, point SN2, point SO2, point SP2, point SQ2, point SR2, point SS2, point ST2, point SU2, and point SV2, the variable magnetization of the free magnetic layer is pinned more firmly than necessary and is not rotated with high sensitivity relative to an applied external magnetic field, and read output in a low frequency band of approximately 10 to 20 MHz is decreased to less than the practical lower limit of 1.2 mV.
Furthermore, by setting the range to inside of point SE2 and SV2, it is not necessary to decrease the product of the remanence and the thickness of the hard bias layers for stabilizing the variable magnetization of the free magnetic layer to less than the value required for more reliably avoiding the instability in regenerated waveform as the track width is decreased.
When the read track width Tw is changed, a magnetic field from the hard bias layers which affects the free magnetic layer also changes, and the appropriate magnetostriction range of the free magnetic layer changes with the track width. In the present invention, by defining magnetostriction ranges of the free magnetic layer at various track widths, it is possible to prevent distortion of regenerated waveforms and instability, and necessary and sufficient read output is obtained.
Consequently, the magnetostriction can be controlled, and it is possible to improve the output characteristics of the spin-valve thin-film magnetic element as the track width is narrowed.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 42 as point (Tw, xcexs), may be within the range obtained by linking point SB1 (0.35, 8), point SC1 (0.3, 12.5), point SD1 (0.25, 18), point SE1 (0.23, 20), point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), point SQ1 (0.2, xe2x88x920.7), point SR1 (0.22, xe2x88x922), point SS1 (0.25, xe2x88x923), point ST1 (0.3, xe2x88x925), and point SU1 (0.35, xe2x88x926.3). Consequently, in particular, in a magnetic head with a read track width of 0.35 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 43 as point (Tw, xcexs), may be within the range obtained by linking point SB2 (0.35, 6), point SC2 (0.3, 7.5), point SD2 (0.25, 10.5), point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), point SR2 (0.23, xe2x88x920.5), point SS2 (0.25, xe2x88x921), point ST2 (0.3, xe2x88x921.5), and point SU2 (0.35, xe2x88x921.6). Consequently, in particular, in a magnetic head with a read track width of 0.35 xcexcm or less, distortion of regenerated waveforms and instability are effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 42 as point (Tw, xcexs), may be within the range obtained by linking point SC1 (0.3, 12.5), point SD1 (0.25, 18), point SE1 (0.23, 20), point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), point SQ1 (0.2, xe2x88x920.7), point SR1 (0.22, xe2x88x922), point SS1 (0.25, xe2x88x923), and point ST1 (0.3, xe2x88x925). Consequently, in particular, in a magnetic head with a read track width of 0.3 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 43 as point (Tw, xcexs), may be within the range obtained by linking point SC2 (0.3, 7.5), point SD2 (0.25, 10.5), point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), point SR2 (0.23, xe2x88x920.5), point SS2 (0.25, xe2x88x921), and point ST2 (0.3, xe2x88x921.5). Consequently, in particular, in a magnetic head with a read track width of 0.3 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 42 as point (Tw, xcexs), may be within the range obtained by linking point SD1 (0.25, 18), point SE1 (0.23, 20), point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), point SQ1 (0.2, xe2x88x920.7), point SR1 (0.22, xe2x88x922), and point SS1 (0.25, xe2x88x923). Consequently, in particular, in a magnetic head with a read track width of 0.25 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 43 as point (Tw, xcexs), may be within the range obtained by linking point SD2 (0.25, 10.5), point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), point SR2 (0.23, xe2x88x920.5), and point SS2 (0.25, xe2x88x921). Consequently, in particular, in a magnetic head with a read track width of 0.25 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 42 as point (Tw, xcexs), may be within the range obtained by linking point SF1 (0.2, 20), point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), point SP1 (0.19, 0), and point SQ1 (0.2, xe2x88x920.7). Consequently, in particular, in a magnetic head with a read track width of 0.19 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 43 as point (Tw, xcexs), may be within the range obtained by linking point SE2 (0.23, 11), point SF2 (0.22, 12), point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), point SP2 (0.2, 1), point SQ2 (0.22, 0), and point SR2 (0.23, xe2x88x920.5). Consequently, in particular, in a magnetic head with a read track width of 0.23 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 42 as point (Tw, xcexs), may be within the range obtained by linking point SG1 (0.19, 20), point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), point SO1 (0.18, 1), and point SP1 (0.19, 0). Consequently, in particular, in a magnetic head with a read track width of 0.18 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 43 as point (Tw, xcexs), may be within the range obtained by linking point SG2 (0.2, 13.5), point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), point SO2 (0.19, 1.2), and point SP2 (0.2, 1). Consequently, in particular, in a magnetic head with a read track width of 0.2 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 42 as point (Tw, xcexs), may be within the range obtained by linking point SH1 (0.18, 20), point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), point SN1 (0.17, 2), and point SO1 (0.18, 1). Consequently, in particular, in a magnetic head with a read track width of 0.17 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 43 as point (Tw, xcexs), may be within the range obtained by linking point SH2 (0.19, 14.2), point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), point SN2 (0.18, 1.5), and point SO2 (0.19, 1.2). Consequently, in particular, in a magnetic head with a read track width of 0.17 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 42 as point (Tw, xcexs), may be within the range obtained by linking point SI1 (0.17, 20), point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), point SM1 (0.15, 3.5), and point SN1 (0.17, 2). Consequently, in particular, in a magnetic head with a read track width of 0.15 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 43 as point (Tw, xcexs), may be within the range obtained by linking point SI2 (0.18, 15.1), point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), point SM2 (0.15, 3.5), and point SN2 (0.18, 1.5). Consequently, in particular, in a magnetic head with a read track width of 0.15 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 42 as point (Tw, xcexs), may be within the range obtained by linking point SJ1 (0.15, 20), point SK1 (0.1, 20), point SL1 (0.1, 9), and point SM1 (0.15, 3.5). Consequently, in particular, in a magnetic head with a read track width of 0.13 xcexcm or less, necessary read output is ensured while distortion of regenerated waveforms and instability are suppressed.
In the present invention, the magnetic read track width Tw (xcexcm) and the magnetostriction xcexs (xc3x9710xe2x88x926), which are shown in FIG. 43 as point (Tw, xcexs), may be within the range obtained by linking point SJ2 (0.15, 17.5), point SW2 (0.13, 20), point SK2 (0.1, 20), point SL2 (0.1, 9), point SX2 (0.13, 5), and point SM2 (0.15, 3.5). Consequently, in particular, in a magnetic head with a read track width of 0.13 xcexcm or less, distortion of regenerated waveforms and instability are more effectively suppressed, and necessary read output is ensured while the hard bias layers are set so that the product of the remanence and the thickness of the hard bias layers is suitable for controlling the magnetic read track width.
In the present invention, the ratio of the width in the track width direction of the free magnetic layer to the height in the element height direction of the free magnetic layer may be set at 1:1 to 3:2, and the height of the free magnetic layer may be in the range of 0.06 to 0.4 xcexcm. Consequently, the single-domain state in the height direction can be improved by shape magnetic anisotropy due to its oblong shape, thus Barkhausen noise, etc., which causes instability, is suppressed.
In the present invention, the spin-valve thin-film magnetic element may be a bottom-type single spin-valve element in which at least the antiferromagnetic layer, the pinned magnetic layer, the nonmagnetic conductive layer, and the free magnetic layer are deposited in that order on the substrate; a top-type single spin-valve element in which at least the free magnetic layer, the nonmagnetic conductive layer, the pinned magnetic layer, and the antiferromagnetic layer are deposited in that order on the substrate; or a dual spin-valve element in which the nonmagnetic conductive layer, the pinned magnetic layer, and the antiferromagnetic layer, one each, are deposited on either surface in the thickness direction of the free magnetic layer. The antiferromagnetic layer may be composed of one of an X-Mn alloy and a Ptxe2x80x94Mnxe2x80x94Xxe2x80x2 alloy, where X is one element selected from the group consisting of Pt, Pd, Ir, Rh, Ru, and Os, and Xxe2x80x2 is at least one element selected from the group consisting of Pd, Cr, Ru, Ni, Ir, Rh, Os, Au, Ag, Ne, Ar, Xe, and Kr. At least one of the pinned magnetic layer and the free magnetic layer may be divided into two sublayers by a nonmagnetic intermediate layer to produce a ferrimagnetic state in which the magnetization directions of the sublayers are antiparallel to each other.
With respect to a spin-valve thin-film magnetic element in which a free magnetic layer is divided into two sublayers by a nonmagnetic intermediate layer, an exchange coupling magnetic field, which directs the magnetizations of the free magnetic sublayers antiparallel to each other, is generated to produce a ferrimagnetic state, and thus the magnetic thickness is decreased. Therefore, the magnetization of the free magnetic layer can be rotated with high sensitivity relative to an external magnetic field.
With respect to a spin-valve thin-film magnetic element in which a pinned magnetic layer is divided into two sublayers by a nonmagnetic intermediate layer, an exchange coupling magnetic field, which directs the magnetizations of the pinned magnetic sublayers antiparallel to each other, is generated to produce a ferrimagnetic state, and thus the magnetic stability is improved.
Furthermore, the objects of the present invention are achieved by a thin-film magnetic head provided with the spin-valve thin-film magnetic element described above.
Additionally, in the spin-valve thin-film magnetic element having a multilayered structure including metallic films, the upper and lower surfaces thereof and a back side in the height direction are covered by an insulating film (gap film) composed of Al2O3 or the like, and a front side (ABS) opposite to the back side is exposed to outside, and it is possible to control the tensile stress in the height direction (element height direction) applied to the free magnetic layer can be controlled by adjusting the compositions of the gap film and the free magnetic layer, and the deposition conditions.